:root {
  color-scheme: light;
  --ink: #243538;
  --muted: #54676a;
  --paper: #fbfaf3;
  --white: #fff;
  --teal: #237f7b;
  --teal-dark: #155d5a;
  --blue: #3c70b7;
  --amber: #d88922;
  --red: #9c3636;
  --line: #d8e0d9;
  --soft: #edf5f2;
  --shadow: 0 12px 30px rgb(36 53 56 / 8%);
  font-family: ui-rounded, "Arial Rounded MT Bold", "Noto Sans KR", system-ui, sans-serif;
  font-synthesis: none;
  text-rendering: optimizeLegibility;
}

* { box-sizing: border-box; }
body { margin: 0; background: var(--paper); color: var(--ink); line-height: 1.55; }
a { color: var(--teal-dark); text-underline-offset: .2em; }
a:hover { text-decoration-thickness: 2px; }
button, input { font: inherit; }
button, .button {
  min-height: 56px; border: 2px solid var(--teal-dark); border-radius: 18px; padding: .75rem 1.1rem;
  background: var(--teal-dark); color: var(--white); font-weight: 800; cursor: pointer; text-decoration: none;
  display: inline-flex; align-items: center; justify-content: center; gap: .5rem;
}
button:hover, .button:hover { background: #104e4b; }
button.secondary, .button.secondary { color: var(--teal-dark); background: var(--white); }
button.stop { border-color: #852d2d; background: #852d2d; }
button:disabled { opacity: .5; cursor: not-allowed; }
:focus-visible { outline: 4px solid #e2a62a; outline-offset: 3px; }
.skip-link { position: fixed; z-index: 20; left: 12px; top: 12px; transform: translateY(-150%); padding: .7rem 1rem; background: #fff; border-radius: 12px; }
.skip-link:focus { transform: translateY(0); }
.site-header { position: sticky; top: 0; z-index: 10; display: flex; align-items: center; justify-content: space-between; gap: 1rem; padding: .65rem max(16px, calc((100vw - 1180px) / 2)); border-bottom: 1px solid var(--line); background: rgb(251 250 243 / 96%); backdrop-filter: blur(10px); }
.brand { display: flex; align-items: center; gap: .65rem; color: var(--ink); font-size: 1rem; font-weight: 900; text-decoration: none; line-height: 1.2; }
.brand small { display: block; color: var(--muted); font-size: .9rem; font-weight: 600; }
.brand-mark { display: grid; place-items: center; width: 44px; height: 44px; border-radius: 14px; background: var(--teal); color: white; font-size: 1.5rem; }
.site-header nav, .site-footer nav { display: flex; align-items: center; gap: .35rem; }
.site-header nav a { min-height: 44px; padding: .55rem .7rem; border-radius: 12px; color: var(--ink); font-weight: 750; text-decoration: none; }
.site-header nav a:hover { background: var(--soft); }
main { min-height: calc(100vh - 150px); }
#app { width: min(1180px, 100%); margin: 0 auto; padding: 1.4rem 16px 3rem; }
.site-footer { display: flex; justify-content: space-between; align-items: center; gap: 1rem; padding: 1rem max(16px, calc((100vw - 1180px) / 2)); background: #eef2eb; color: var(--muted); font-size: .9rem; }
.site-footer p { margin: 0; }
.hero { position: relative; overflow: hidden; display: grid; grid-template-columns: minmax(0, 1.3fr) minmax(230px, .7fr); gap: 1.5rem; align-items: center; padding: clamp(1.3rem, 4vw, 3rem); border: 1px solid #d9e7df; border-radius: 30px; background: linear-gradient(125deg, #edf6f0 0%, #f4f7eb 70%, #fff4d9 100%); }
.hero h1 { max-width: 13ch; margin: .4rem 0 .7rem; font-size: clamp(2.1rem, 5.2vw, 4.2rem); line-height: 1.1; letter-spacing: -.04em; }
.hero p { max-width: 55ch; color: #40575a; font-size: 1.1rem; }
.hero-art { display: grid; place-items: center; min-height: 220px; font-size: clamp(5rem, 14vw, 10rem); color: var(--teal); }
.hero-art span { display: grid; place-items: center; width: 210px; aspect-ratio: 1; border-radius: 48% 52% 58% 42%; background: radial-gradient(circle at 30% 28%, #fff4c7 0 8%, transparent 9%), radial-gradient(circle at 70% 66%, #d2e9e1 0 48%, #c3e0d7 49%); box-shadow: var(--shadow); transform: rotate(-7deg); }
.eyebrow { margin: 0; color: var(--teal-dark); font-size: 1rem; font-weight: 900; letter-spacing: .07em; text-transform: uppercase; }
.section-heading { display: flex; align-items: end; justify-content: space-between; gap: 1rem; margin: 2.1rem 0 1rem; }
.section-heading h2, .page-title { margin: 0; font-size: clamp(1.6rem, 3.5vw, 2.5rem); line-height: 1.2; letter-spacing: -.025em; }
.section-heading p { margin: .35rem 0 0; color: var(--muted); }
.card-grid { display: grid; grid-template-columns: repeat(3, minmax(0, 1fr)); gap: 1rem; }
.experiment-card { display: flex; flex-direction: column; gap: .6rem; min-height: 225px; padding: 1.15rem; border: 1px solid var(--line); border-radius: 22px; background: var(--white); box-shadow: 0 4px 14px rgb(36 53 56 / 4%); }
.experiment-card h3 { margin: .2rem 0 0; font-size: 1.25rem; line-height: 1.3; }
.experiment-card p { margin: 0; color: var(--muted); }
.experiment-card .card-foot { display: flex; flex-wrap: wrap; gap: .45rem; margin-top: auto; padding-top: .5rem; }
.category-nav { display: grid; grid-template-columns: repeat(5, minmax(0, 1fr)); gap: .65rem; margin: 1.25rem 0 1.8rem; }
.category-jump { display: flex; flex-direction: column; min-width: 0; min-height: 68px; gap: .1rem; padding: .65rem; color: var(--teal-dark); background: white; border-color: #b9d1c9; border-radius: 16px; text-align: center; line-height: 1.25; }
.experiment-card .button { min-height: 48px; width: 100%; margin-top: auto; }
.toolbar .button, .toolbar button, .choice-list button { min-height: 48px; }
.category-jump:hover { color: white; }
.category-jump small { color: var(--muted); font-size: 1rem; font-weight: 650; }
.category-jump:hover small { color: #e7f3ef; }
.activity-category { margin-top: 2.2rem; scroll-margin-top: 1rem; }
.category-heading { margin-bottom: .9rem; }
.category-heading h2 { margin: .15rem 0; font-size: clamp(1.45rem, 3vw, 2rem); line-height: 1.2; }
.category-heading > div > p:last-child { margin: .25rem 0 0; color: var(--muted); }
.activity-category .card-grid { scroll-margin-top: 1rem; }
.pill { min-height: 32px; display: inline-flex; align-items: center; gap: .25rem; padding: .35rem .65rem; border-radius: 999px; background: #edf4f1; color: #245e5a; font-size: .9rem; font-weight: 800; line-height: 1.35; }
.pill.caution { color: #714812; background: #fff1d4; }
.notice { padding: 1rem 1.1rem; border: 1px solid #e9ca88; border-left: 6px solid var(--amber); border-radius: 16px; background: #fff6e3; color: #573c17; }
.notice strong { display: block; margin-bottom: .15rem; }
.notice p { margin: .25rem 0 0; }
.review-banner { margin: 1rem 0; padding: .9rem 1rem; border: 1px solid #e7cf9c; border-radius: 16px; background: #fff9e8; color: #654919; font-weight: 750; }
.page-head { display: flex; justify-content: space-between; align-items: start; gap: 1rem; margin: .3rem 0 1.2rem; }
.page-head p { max-width: 65ch; color: var(--muted); }
.content-panel { margin: 1rem 0; padding: clamp(1rem, 3vw, 1.6rem); border: 1px solid var(--line); border-radius: 22px; background: var(--white); }
.content-panel h2, .content-panel h3 { margin-top: 0; }
.content-panel p:last-child, .content-panel ul:last-child, .content-panel ol:last-child { margin-bottom: 0; }
.columns { display: grid; grid-template-columns: repeat(2, minmax(0, 1fr)); gap: 1rem; }
.check-list { display: grid; gap: .55rem; padding: 0; list-style: none; }
.check-list li { display: flex; align-items: start; gap: .6rem; }
.check-list li::before { content: "✓"; display: grid; flex: 0 0 26px; width: 26px; height: 26px; place-items: center; border-radius: 50%; background: #e5f2ed; color: #155d5a; font-weight: 900; }
.materials { display: flex; flex-wrap: wrap; gap: .5rem; padding: 0; list-style: none; }
.materials li { display: grid; gap: .25rem; padding: .5rem .75rem; border-radius: 12px; background: #eef3f1; }
.materials li small { color: var(--muted); font-size: 1rem; line-height: 1.5; }
.choice-list { display: grid; grid-template-columns: repeat(auto-fit, minmax(180px, 1fr)); gap: .7rem; }
.choice-list button { min-height: 64px; color: var(--teal-dark); background: white; }
.choice-list button:hover { background: #eaf4ef; }
.choice-list button[aria-pressed="true"], .choice-list button[aria-pressed="true"]:hover { color: #ffffff; background: var(--teal-dark); }
.screen-result { margin-top: 1rem; padding: 1rem; border: 1px solid #9cbab1; border-radius: 16px; background: var(--soft); }
.screen-result h3 { margin: .2rem 0 .8rem; }
.screen-result h4 { margin: 1rem 0 .3rem; font-size: 1.05rem; }
.page-title:focus { outline: 4px solid #e2a62a; outline-offset: 4px; border-radius: 4px; }
.step-card { max-width: 780px; margin: 1rem auto; padding: clamp(1.2rem, 4vw, 2rem); border: 2px solid #c4ded5; border-radius: 28px; background: white; box-shadow: var(--shadow); }
.step-card .step-count { color: var(--blue); font-weight: 900; }
.step-card .step-copy { font-size: clamp(1.3rem, 3.4vw, 2rem); font-weight: 750; line-height: 1.4; }
.step-actions { display: flex; flex-wrap: wrap; gap: .7rem; justify-content: space-between; margin-top: 1.3rem; }
.timer-box { display: flex; flex-wrap: wrap; align-items: center; justify-content: space-between; gap: .7rem; margin: 1rem 0; padding: .9rem 1rem; border-radius: 16px; background: #eef4fc; }
.timer-value { color: #234f8c; font-size: 1.3rem; font-weight: 900; font-variant-numeric: tabular-nums; }
.timer-note { flex-basis: 100%; margin: 0; color: var(--muted); font-size: 1rem; line-height: 1.5; }
.guardian-form { display: grid; gap: .7rem; margin: 1rem 0; }
.guardian-form label { display: flex; gap: .75rem; align-items: start; min-height: 56px; padding: .8rem; border: 1px solid var(--line); border-radius: 14px; background: white; }
.guardian-form input { width: 24px; height: 24px; accent-color: var(--teal); }
.source-access-check { display: flex; align-items: center; gap: .75rem; min-height: 56px; margin: 1rem 0; padding: .8rem; border: 1px solid var(--line); border-radius: 14px; background: var(--white); font-weight: 750; }
.source-access-check input { width: 24px; height: 24px; flex: 0 0 24px; accent-color: var(--teal); }
.toolbar { display: flex; flex-wrap: wrap; gap: .65rem; margin: 1rem 0; }
.empty-state { padding: 2rem 1rem; border: 1px dashed #9cbab1; border-radius: 20px; text-align: center; color: var(--muted); }
.source-list { display: grid; gap: .7rem; padding: 0; list-style: none; }
.source-list li { padding: .85rem; border: 1px solid var(--line); border-radius: 14px; }
.source-list p { margin: .35rem 0 0; color: var(--muted); }
.timer-label { font-weight: 800; }
.sr-only { position: absolute; width: 1px; height: 1px; padding: 0; margin: -1px; overflow: hidden; clip: rect(0, 0, 0, 0); white-space: nowrap; border: 0; }
.print-card { max-width: 800px; margin: auto; padding: 1rem; border: 2px solid #333; background: white; color: #111; }
.print-card h1 { font-size: 2rem; }
.print-card h2 { margin-top: 1.4rem; border-bottom: 1px solid #777; }
.print-card li { margin: .35rem 0; }

@media (max-width: 760px) {
  .site-header { align-items: start; flex-direction: column; gap: .45rem; }
  .site-header nav { width: 100%; overflow-x: auto; }
  .site-header nav a { flex: 1 0 auto; text-align: center; }
  .hero { grid-template-columns: 1fr; }
  .hero-art { min-height: 130px; }
  .hero-art span { width: 130px; }
  .card-grid { grid-template-columns: repeat(2, minmax(0, 1fr)); }
  .category-nav { grid-template-columns: repeat(3, minmax(0, 1fr)); }
  .site-footer { align-items: start; flex-direction: column; }
}
@media (max-width: 500px) {
  #app { padding-top: .8rem; }
  .card-grid, .columns { grid-template-columns: 1fr; }
  .category-nav { grid-template-columns: repeat(2, minmax(0, 1fr)); }
  .experiment-card { min-height: auto; }
  .page-head { flex-direction: column; }
  .section-heading { align-items: start; flex-direction: column; }
  .button, button { width: 100%; }
  .toolbar button, .toolbar .button { width: 100%; }
}
@media (prefers-reduced-motion: reduce) {
  *, *::before, *::after { scroll-behavior: auto !important; animation-duration: .01ms !important; animation-iteration-count: 1 !important; transition-duration: .01ms !important; }
}
@media print {
  body { background: white; }
  .site-header, .site-footer, .skip-link, .no-print, .review-banner { display: none !important; }
  #app { width: 100%; padding: 0; }
  .print-card { border: 0; padding: 0; }
  .print-card h1 { font-size: 20pt; }
  .print-card h2 { break-after: avoid; }
}